1. Technical Field
The present invention relates to a resonator element, a resonator, an oscillator, an electronic device and a mobile object.
2. Related Art
Hitherto, resonator elements using a quartz crystal have been known. Such resonator elements have excellent frequency-temperature characteristics, and thus have been widely used as a reference frequency source or a transmission source of various electronic devices.
A resonator element disclosed in JP-A-2008-72705 is formed in a tuning fork type, and includes a resonator blank provided with a base portion, a pair of vibrating arms extending from one end side of the base portion, a connecting portion which is located on the other end side of the base portion, a coupling portion, located between the base portion and the connecting portion, which couples the base portion to the connecting portion, and a support arm extending from the connecting portion.
Such JP-A-2008-72705 discloses that e/r which is a ratio between a width r of the coupling portion and a width e of the base portion is preferably equal to or less than 40%, and is more preferably 23% to 40%. As an effect of satisfying such ranges, the above document discloses a technique capable of maintaining impact resistance while suppressing vibration leakage. However, even when e/r satisfies the above relation, the impact resistance is not able to be maintained depending on design conditions (for example, thickness of a resonator blank), and thus the resonator element may have a tendency to be broken. In addition, JP-A-2008-72705 discloses that the thickness of the resonator blank is preferably 70 μm to 130 μm (see paragraph 0042 of JP-A-2008-72705), but the relationship between the thickness and e/r is not obvious.